User Manual

EP7309/11/12 User’s Manual - DS508UM4 13-1

1313

Chapter 13

13Dedicated LED Flasher

Introduction

LED flasher provides a user interface to toggle a specific GPIO pin for use to flash an

LED or oth er signaling device. A benefit of this feature is that the system, regardless

of th e processor state, will continue to control this port. Only a system reset, loss of

power, or malfunction wou ld prevent normal operation of the LED flasher.

LED Flasher Register List

Programming Example

;*****************************************************************************

; Program PD0/LEDFLSH for 50% duty on a 1 sec interval

;*****************************************************************************

LEDFLSH EQU 0x61

;

ldr r0, =0x80002000

mov r1, #LEDFLSH

str r1, [r0,#0x2C0]

;

Operational Overview

The LED flasher feature enables an external GP IO ( PD0 / LEDFLSH)tobetoggledata

programmable rate an d duty cycle with the intent of u sing this to toggle an LED. If

programmed,

PD0 will be dedicated to this task.

This module is driven from the RTC (32.768 kHz) oscillator and works in all running

modes because no CPU intervention is required.

The flash rate can be programmed from 1-4 seconds, and the duty cycle can vary from

1/15 to 15/16 with a 50% duty cycle at 8/ 16. The external p in can provide up to 4 ma

of dr ive current.

Table 13-1: LED Flasher Registers

Address Name Type Size Description Page

0x8000.22C0 LEDFLSH R/W 0 LED Flasher page 13-2